The present invention generally relates to electrical apparatus and, in a preferred embodiment thereof, more particularly relates to an electric water heater which incorporates therein apparatus that substantially simplifies the conversion of the water heater between single phase and three phase operation thereof.
Electric water heaters are typically manufactured for use with either a single or three phase electric power supply, and may normally be later converted from single to three phase operation or vice versa. The manufactured electric water heaters are often shipped to warehouses or other holding areas to await delivery to a purchaser. It is often the case that a purchaser needs an electric water heater having a given heating capacity and, for example, being operable with single phase electrical power. If the warehouse has a water heater with the desired heating capacity but manufactured to be operated with three phase electrical power the water heater must be converted at the warehouse to single phase operation (or converted from single to three phase operation as the case may be) before the water heater is delivered to the purchaser.
Modern electric water heaters are often manufactured with multiple immersion type electrical resistance type heating elements, each having an associated thermostat. The thermostats are typically connected through fuse holders to the load side of a terminal structure via what may be a large number of individual wires. AS an example, for an electric water heater having nine heating elements there would typically be 18 individual wires operatively connected to the load side of the terminal structure. When it becomes necessary to change the water heater from one phase operation to another phase operation it is conventionally necessary to individually relocate most or all of these wires on the terminal structure in accordance with a phase conversion wiring diagram provided with the water heater.
As might be imagined, this is a laborious, time-consuming task that must be carefully performed if the phase-converted water heater is to function properly. This laborious phase conversion task, of course, is not limited to electrical water heaters, but is necessary in a wide variety of other electrical devices that may be rewired to convert the phase of their electrical operation. A need thus exists to provide simplified phase conversion apparatus for an electrical device such as an electric water heater. It is to this need that the present invention is directed.